For thirty years at least, I have designated myself as a zoologist interested in the “philosophical aspects of biology”. But I have now to admit that not until within the last two or three years have I recognized that logic, particularly in its inductive aspect, is involved in such interest.

For me as a zoologist with a predilection for natural history, observation has had a place of wide application and of implicit confidence. Until recently, I had rested in the supposition that after all of the devices practiced by naturalists to insure certainty of their observations, nothing further was needed so far as the information and understanding they gained was concerned. I had gone ahead with my reasoning, my logic, with no more qualms about the trustworthiness of the “inductive” than of the “deductive” side of it. I had not taken seriously the assertion, made years ago in my hearing by an eminent philosopher, that no one can be a philosopher without being skeptical and critical of the use of his senses in getting knowledge. Latterly, however, I have come to see that traditional philosophers take themselves very seriously in such assertions. This realization has been due to the discovery that the recent advances in physics and mathematics have led most of the leaders in these fields to believe that observation and the inductive side of logic may be left where they were a hundred years ago. These scientists seem to be about where John Stuart Mill was in his effort to improve Lord Bacon's effort for a better understanding of both observation and induction.

In a recent paper I criticized the pragmatist theory of truth from the frame of reference of modern logical positivism (scientific empiricism). By showing the similarity between Karl Mannheim's claims of epistemological relevance for sociology of knowledge and certain pragmatist notions concerning truth I made criticism of the latter with the former. The aim of this present paper is to extend and elaborate upon those critical remarks regarding pragmatism both in order to answer objections raised since and to clarify what was said there. Moreover, the evaluation of the pragmatist theory of truth may have been surprising to some since so much lately has been made of the points of agreement between pragmatism and modern positivism. It is thus also my intent to delimit agreements and disagreements and compare the respective emphases in pragmatist and positivist thought concerning the nature of truth.

The first thing to realize about grading as a psychological process is that it precedes measurement and counting. Judgments of the type “A is larger than B” or “This can contains less milk than that” are made long before it is possible to say, e.g., “A is twice as large as B” or “A has a volume of 25 cubic feet, B a volume of 20 cubic feet, therefore A is larger than B by 5 cubic feet,” or “This can contains a quart of milk, that one 3 quarts of milk, therefore the former has less milk in it.” In other words, judgments of quantity in terms of units of measure or in terms of number always presuppose, explicitly or implicitly, preliminary judgments of grading. The term four means something only when it is known to refer to a number which is “less than” certain others, say five, six, seven, arranged in an ordered series of relative mores and lesses, and “more than” certain others, say one, two, three, arranged in an ordered series of relative mores and lesses. Similarly, a foot as a unit of linear measure has no meaning whatever unless it is known to be more than some other stretch, say an inch, and less than a third stretch, say a yard.

The complexity and the technical obscurity of the scientific method have rendered science ever likely to be misunderstood both by scientists themselves and by the general public. Difficulties which remain unrecognized constitute the most formidable obstacles to success in any field. There are such difficulties lurking in the treatment which the scientific method accords its subject-matter. In this essay, I propose to point to one such pitfall in the path of the progress of science. By exposing it, something will already be accomplished toward its avoidance and elimination, and the vast public of uninstructed persons will be able to skirt one more confusion in the effort to understand what the scientists are trying to do.